Automatic restraint and visual detection of fatigue crack growth by applying an alumina paste

I. Takahashi, M. Ushijima, C. Takahashi, S. Uematsu, N. Kotani

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


A paste comprising fine alumina particles was applied on surfaces of steel plate specimens and a welded joint specimen, and the effects of the paste on restraint and visual detection of fatigue crack growth were experimentally investigated by performing fatigue tests with in situ observations by a charge coupled device (CCD) microscope and through various kinds of fractographic observations and elemental analyses using an scanning electron microscope (SEM) and an electron probe microanalyser (EPMA). As a result, the crack growth rate in the plate specimen was drastically retarded by the wedge effect of the alumina particles, and a 311% increase in failure life was produced on an average. The restraint of crack opening displacement (COD) value by the wedge materials was estimated by elastic finite element (FE) analyses, and the results were compared with the experimental data. Similar crack growth restraint effects were also observed on the welded joint specimen, producing a 117% increase in failure life. In the fatigue tests of the specimens on which the alumina paste was applied, a remarkable black colour developed in the white alumina paste along the paths of crack propagation, facilitating the visual detection of the cracks. An analysis using an X-ray diffractometer showed that the black matter in the paste consists of fine debris derived from the base metal.

Original languageEnglish
Pages (from-to)832-843
Number of pages12
JournalFatigue and Fracture of Engineering Materials and Structures
Issue number9
Publication statusPublished - 2007 Aug
Externally publishedYes


  • Alumina paste
  • Crack closure
  • Crack opening displacement
  • Fatigue crack growth
  • Fine particles
  • Fractography
  • Retardation
  • Stress intensity factor
  • Visualdetection
  • Wedge effect
  • Welded joint

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering


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